Polyamide has been utilized extensively as a synthetic fiber. While its structural and mechanical properties make it attractive for use in such capacities as carpeting, it is nonetheless relatively expensive. It would therefore be desirable to replace a portion of polyamide fibers with a core formed from a relatively lower cost non-polyamide material. However, replacing a portion of a 100% polyamide fiber with a core portion of a relatively less expensive non-polyamide material may affect the mechanical properties of the fiber to an extent that it would no longer be useful in its intended end-use application (e.g., as a carpet fiber).
Furthermore, as evidenced by U.S. Pat. No. 5,208,107 (the entire content of which is expressly incorporated hereinto by reference), hollow trilobal fibers have been proposed in the past so as to provide desirable "cover" and soil hiding properties. In essence, these conventional hollow trilobal filaments are characterized by a total cross-section void area of between about 3 and about 10 percent and have a single approximately axially extending central void.
It would therefore be highly desirable if sheath-core bicomponent filaments could be provided so as to minimize expenses associated with the higher cost sheath component. At the same time it would be desirable if such bicomponent filaments were provided with longitudinally extending central voids so as to provide the cover, luster and soil hiding characteristics associated conventional hollow trilobal filaments. It is towards fulfilling such needs that the present invention is directed.